Process of producing reactive zeolites.



UNITED STATES PATENT OFFICE.

THOMAS n. DUGGAN, OF NEW YORK, N. Y., ASSIGNOR TO THE PERMU'IIT COMPANY,on NEW YORK, N. Y., A CORPORATION OF DELAWARE.

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$pecification of Letters Patent.

Patented Nov. 3, 1914.

Application filed July 12,1913. Serial NO. 778,712.

stances as may be necessary to obtain a hard glassy melt containingabout half its weight of alumina and silica (in a ratio of approximately1:2 or 2:5), the residue consisting of soda and potash with a ratio ofapproximately 5:1 and the material thus obtained is converted into'hardgrained highly reactive material by granulation and treat:

ment with water in a methodical way; all

as more fully hereinafter set forth and as claimed.

In the purification of water and of other liquids, a process of fixingand removing impurities with the aid of certain hydrated insolublesilicates (exchange silicates) has come into use. In this process, afused composition of a glassy nature, containing both silica and aluminaunited to bases is first provided, this composition being of such achemical constitution that it can be hydrated to give an .insolublematerial readily reactive with aqueous solutions. If, for example, afused composition be made with correct proportions of silica, aluminaand alkali and this composition be then hydrated, the hydratedcomposition on contact with a hard water is found to exchange bases,

taking up lime and magnesia in an insoluble form and giving up acorresponding amount of alkali to the solution. Water may thus berapidly and effectually freed of hardness-giving solubles, suchas'sulfate and carbonate of lime. 'Suitable zeolites may be devised forremoving other solubles, such as iron, manganese, otash, etc., fromwater orother liquidsa he exchange is in the nature of a mass action.When the ab sorption of lime begins to slow up by reason of the zeolitebeing charged therewith, the

out bein reverse exchange can be efi'ected by washing the zeolite with asolution of a salt of an alkaline base. The lime and magnesia now gointo solution while the alkali takes their placein the zeolite. Afterwashing out the soluble salt, the zeolite is ready for re-use. Thisalternating process of removing lime from water and revivifying may becarried on indefinitely. In practice, hard water is filtered through agranular bed of soda zeo lite until the'zeolite has taken up a certainamount of lime and then a brlne is run through the zeolite bed to reviveit. In the described process, which has gone into extensive use, thecapacity of a given installation for the treatment of water or otherliquid of course depends not only on the chemical nature and degree ofhydration of the zeolite and consequently its powers of exchange, butalso very materially upon its physical character. filter or treatmentbed should be as granular and porous and offer as much surface as possible to liquid flowing through'the bed withso soft as to mash down orchannel readi y. The chemical and hysical re-' quirements are somewhatconflicting and the physical conditions are best satisfied by a zeolitein rather small granules of a particular hard yet open texture sincenat- I .urally the greater the surface of the zeolite which can beexposed to water orthe like the more liquid can be treated by a givenweight of itin a time unit. Nevertheless thishard material must be,highly reactive chemically. The methods heretofore proposed forproducing such material have not given these qualities to such an extentas is desirable Much depends on the composition of the melt and on thetreatment to whichit .is afterward exposed. Some com positions ontreatment with water are apt sustain the weight of a bed. having a con-'siderable thickness of material, hard enough to resist erosion andbreaking up or channeling by the action of flowing currents of liquid,and of such a shape as not to com pact and reduce the porosityof themass;

. while further the granules must be of such character as to expose asmuch surface as possible to the flowing liquid; a surface greater thantheir sheer outside surface that is, they, must be more or less porous.It is the purpose of the present invention to provide such a material;to give a highly reactive zeolite having good chemical and physicalproperties, being porous and of large surface while at the same time ofrelatively strong and resistant physical character and being also highlyreactive chemically.

I have found that in making a highly reactive zeolite for waterpurification and the of potash for the soda usually employed.

The proportion of K 0 to N21 O should be about 1:5 but maybe raisedsomewhat. This potash is best obtained from natural potassiferous rocks,such as feldspar, phonolite, leu'cite, etc., wherein it occurs insilicate combination together with alumina. Orthoclase feldspar is oneofthe minerals best adapted for my pur oses since it carries potash,alumina an silica in a com-. bined form, readily capable of undergoingmolecular rearrangements to give the particularglassy compounds heredesired. Feldspar contains a relatively high amount of combined silicaand for this reason also is a nod component ofaraw mix formaking thefused glassy melt; free silica, as quartz or sand entering into reactionto form the melt rather slowly. and being apt to give compositions ofirregular character. A good composition maybe made by melting together56 parts of sodiumv carbonate or soda ash, 25 to 26 parts of feldspar,12 parts of kaolin and 6 or 7 parts of potassium car- '.bonat'e. Otherproportions and other materials may be used in making the mix, using theordinary stoichiometric 'fprinciples to obtain about the. same ratiosoalumina,

silica, soda andjpotash'. With the mixture may be used moreor less ofthe preformed glassy materialto-act as a flux, as such an additionmaterially quickens the rate of the fusion and the molecularrearrangement to which the formation of the zeolite yieldingcompoLm'ds-is-due. Phonolite, leucite, eta,

ma y be substituted for the feldspar. In the mix for the'glassy melttherelative amounts hot water.

much as may be of the potash,"silica and alumina from the readilyfluxing and. read-' ily reacting orthoclase. The mixed mate- .rials maybe fused on the hearth of any suitable furnace at a temperature between1250 to 1500 C. As stated, an admixture of previously made material isdesirable. After fusion the material will be found to be of atransparent glassy nature and, usually, of green color. It fracturesreadily.

The use of both soda and potash in the melt in some way. operates in thesubsequent treatment to give granules of better physical and chemicalcharacter. In making the zeolite, that is in the hydrating and washingout operations, much of the potash of the melt goes into solution butthe finished zeolitic material still contains both potash and soda.After employment of the zeolite once or twice in purifying hard waterand revivification with salt solution, most or all i of this potashdisappears and is replaced by soda, but the advantageous physical andchemical characteristics of the zeolite re main. The potash thoughuseful in mak ing the zeolite is a replaceable base which may beremoved.

The glassy fused mass so obtained is, so to speak, a raw material andrequires further treatment to obtain zeolites suitable for purifyingwater and other liquids. As made, it contains an excess of solublebodies which must be removed; the material must be hydrated and it mustbe formed into granules of appropriate size and strength with asgood aporosity as may be. Itherefore treat the fused materials in a specialway. They glassy material is first crushed by any suitable means, suchas rolls, and is thereafter sifted. It is best in this sifting operationto select fragmentsbetween 11} and 9 mm. diameter. The dust and finesmay be sent back to the furnace and admixed with a fresh charge, therebynot only securing an economy in. operation but also the statedadvantageous fluxing effect of preformed material. Larger pieces may berecrushed. The granules thus obtained are sharp-edged, glassy fragments,are irregular in shape and are usually of a light green color. The nextstep is to place the granules in a "shallow layer in a bath of boilingor Cold water with this material gives undesirable effects.Advantageously the layers may be supported on wire mesh trays in a bathof suitable character. The temperature of the water in this treatmentmay be between 90 and 100 C. Atemperature of 90 C. is advantageous.Treatment with water at this temperature is continued for two or threehours during which time the glassy granules swell and burst into smallersized pieces. The bath may be kept -hot by' steam. The water may bechanged fromtime to time; or a continuous slow may be concentrated andthese bodies recovered. The expanded hydrated granules are next furthercrushed and sized to a diameter of about 2 mm. The granules are thenwashed or leached with water which may be cold or warm, until the washwater shows but little alkalinity. 'It is advantageous' however to usehot and cold water, at 90 C. and at 15 C. alternately. Thenumber'of-leachings of course depends on the circumstances but often 15treatments with each are em loyed. Washing may be con sidered sufficientwhen 25 cc. of-wash Water do not require more than 5 drops of normalacid for neutralization. The washing may be done in a continuous manner,using-the countercurrent principle; orthe granules may be ,washedinanumberof separate baths. Where separate baths are used, ordinarily 20to 30 washings will begsuflicient. The washed granules are next resiftedin water, using about 912 mm. mesh. They may then be dried in acentrifugal machine to give the finished zeolite.

The finished material consists of granules ranging between .5 and 2 mm.diameter. Ifiner material is rejected. These granules are of a lightbrownish color, are opaque, granular and more or less porous. Theyappear moist at first but on exposure to air dry down and become white.As the material leaves the centrifugals itcontains about 5O per cent. ofwater of which 11 to 14 per cent. represents water of constitutionor'hydration, the remainder being moisture. In a properly arrangedfilter bed, the

anules will take up about 3.5 per cent. of lime (CaO). before the rateog absorption becomes so slow as to make revivification advisable; andwith the present material the absorption may be pushed tothe total".disappearance of a ali; that is until all the glassy alkali is replacedby lime. The granules though hard and firm and capable of supportingconsiderable burden without breaking down or mashing, are neverthelessporous throughout. A granule of'the fresh material when phenolphthaleinsolution becomes pink placed in contact with a throughout showing a highdegree of porosity.

What I claim is 2-- 1. In the preparation of zeolitic purifyingmaterials the process which comprises making a fused glassy meltcomprising alumina, sillca, potash and soda with a, ratio of soda topotash of approximately 5:1, granulating and thereafter extracting.alkalis with water.

2. In the preparation of zeolitic purifying materials the process whichcomprises making a fused glassy melt comprising alumina, sillca, potashand soda with a ratlo of soda to potash of approximately 5: 1,granulating and thereafter treating with hot water.

3. In the preparation of zeolitic purifying materials the process whichcomprises making a fused glassy melt comprising alumina, silica, potashand soda with a rationi soda to potash of approximately 5:1,granflitting to a size between 1.5 and 9 mm. diameter'alid thereafterextracting alkalis with water.

4. In-the preparation of zeolitic purifying materials the process whichcomprises making a fused glassy melt-comprising alumina,

v silica, potash and. soda witha ratio of soda to potash ofapproximately 5: 1, granulating to a sizebetween 1.5 and 9 mm. diameter,thereafter treating with hot water and thereafter recrushing to.material of about a 2,

.melt comprising alumina, silica and total alkali in about the ratio of3:7:13, with about five times as much soda as potash, granulating andtreating with hot water.

7. In the preparation of zeolitic water purifying materials the rocesswhich comprises=-'grai1ulating a g assy zeolitic melt,

swelling and hydrating with hot water till all appearance disappears,regranulating, washing and drying.

8. In the preparation of zeolitic purifying materials from zeoliticmelts the process which comprises hydrating such a melt with i hot waterand leaching a plurality of times,

being alternately with hot such leaching water and with water attheordinary tem" perature.

F 9. In the preparation of zeolitic purifying I30 materials vthe processwhich comprises mak-' In testimony whereof, I afiix my signature ini: afused glassy melt of orthoclase and in the presence of two subscribingwitnesses. 0t er materials such melt comprising a alumina, silica aiidtotal alkali in about the DUGGAN ratio of 3:7 :13 with about five timesas Witnesses:

much soda as potash, granulating and treat- R. NICHOLSON, J12, ing withhot water. Y W. R. N IGHOLSON.

